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Lapsed, fee not paid

Converter control of variable-speed wind turbines

US 8,577,508 B2 · Assignee: University of Alabama · Inventors: Li; Shuhui et al.

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Overview

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Why it's free to use

  • The USPTO Official Gazette of December 30, 2025 lists it as expired on November 5, 2025 for an unpaid maintenance fee.
  • It isn't on any reinstatement notice published since.
  • Its 1 US relative has also lapsed, expired or never issued.
  • We check US rights only. Check foreign counterparts before selling abroad.
FiledMay 5, 2008
GrantedNovember 5, 2013
Expired (fee)November 5, 2025
Application number12/532890
Classification (CPC)H02P21/22 +7 more
Length26 pages

Drawings 15

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Claims

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Description

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Timeline & family

Timeline From USPTO dates

200820102012201420162018202020222024Earliest priority dateMay 4, 2007Application filedMay 5, 2008Application publishedMay 6, 2010Patent grantedNov 5, 20133.5-year fee paidMay 5, 20177.5-year fee paidMay 5, 202111.5-year fee not paidMay 5, 2025Patent expiredNov 5, 2025

Maintenance fees

Fees are due 3.5, 7.5 and 11.5 years after grant. This patent expired on November 5, 2025, so the fee marked "not paid" was the one that went unpaid.

3.5-year feeDue May 5, 2017Paid
7.5-year feeDue May 5, 2021Paid
11.5-year feeDue May 5, 2025Not paid

US family 2 documents, by filing date

Published applicationUS 2010/0109328 A1

CONVERTER CONTROL OF VARIABLE-SPEED WIND TURBINES

Filed May 2008 · published May 2010
Published application
This documentUS 8,577,508 B2

Converter control of variable-speed wind turbines

Filed May 2008 · granted Nov 2013
Lapsed, fee not paid

Earlier publications, parents and continuations. None of them can still be enforced, or this patent would not be listed.

US patents it cites 0

No US citations on record.

Sources & verification

Verification

  • The USPTO Official Gazette of December 30, 2025 lists it as expired on November 5, 2025 for an unpaid maintenance fee.
  • It isn't on any reinstatement notice published since.
  • Its 1 US relative has also lapsed, expired or never issued.
  • Rechecked against USPTO records every day.
  • We check US rights only. Check foreign counterparts before selling abroad.

Confirm it yourself

  1. Open the file history on Patent Center.
  2. The status should read "Patent Expired Due to NonPayment of Maintenance Fees Under 37 CFR 1.362".
  3. Check the documents for any later petition to revive or reinstate.

Official USPTO records

USPTO Official GazetteNotice of Expiration of Patents Due to Failure to Pay Maintenance Fee, issue of December 30, 2025.Where this listing came fromMaintenance fee recordEnter the patent number to see its fee history.USPTO FeesFull published documentText and every drawing sheet as a PDF.USPTOFile historyStatus, office actions, notices, fee records and petitions.USPTO Patent CenterPatent Public Search recordSearchable full text and bibliographic data.USPTO

Cross-check elsewhere

Google PatentsWorldwide family, citing patents and legal events.patents.google.comJustia PatentsFull text, claims and classification.patents.justia.comFreePatentsOnlineFull text and PDF.freepatentsonline.comEspacenetForeign family and legal status.European Patent Office

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